The invention relates to compounds having anti-secretory activity, and is particularly concerned with a class of novel 3-alkyl-9-aminoalkyl-1,2,3,4-tetrahydrocarbazoles which are capable of selectively inhibiting gastric acid secretion without causing bronchial constriction or other side effects. These compounds are therefore useful in the treatment of peptic ulcers and other conditions caused or exacerbated by gastric hyperacidity.